Method  of  patterning a stack

ABSTRACT

The embodiments disclose a method of fabricating a stack, including replacing a metal layer of a stack imprint structure with an oxide layer, patterning the oxide layer stack using chemical etch processes to transfer the pattern image and cleaning etch residue from the stack imprint structure to substantially prevent contamination of the metal layers.

BACKGROUND

Contamination of the amorphous carbon layer during milling by residue ofa metal mask may occur when using a metal sub-layer to transfer apattern image from an imprinted resist to the magnetic layer. Theresidue of metal contaminates the amorphous carbon mask layer, resultingin affection of control dimensions bias and fidelity of patterning. Sizeand position control of features during a pattern fabrication processdegrades drastically due to metallic residue mixed up with amorphouscarbon mask layer residue left after stack patterning. Also, such amixture is hard to clean up without affecting magnetic properties of themagnetic layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of an overview of a method of patterning astack of one embodiment.

FIG. 2A shows a block diagram of an overview flow chart of a method ofpatterning a stack of one embodiment.

FIG. 2B shows a block diagram of a continuation of an overview flowchart of a method of patterning a stack of one embodiment.

FIG. 2C shows a block diagram of a continuation of an overview flowchart of a method of patterning a stack of one embodiment.

FIG. 3A shows for illustrative purposes only an example of an oxidelayer imprint structure of one embodiment.

FIG. 3B shows for illustrative purposes only an example of templatepatterning in the resist layer of one embodiment.

FIG. 4A shows for illustrative purposes only an example of UV lightresist curing of the resist layer of one embodiment.

FIG. 4B shows for illustrative purposes only an example of removing thepattern template from the resist layer of one embodiment.

FIG. 5A shows for illustrative purposes only an example of a chemicalde-scum of the pattern imprinted resist layer of one embodiment.

FIG. 5B shows for illustrative purposes only an example of an etching inthe oxide layer of one embodiment.

FIG. 6A shows for illustrative purposes only an example of an etching inthe amorphous carbon layer of one embodiment.

FIG. 6B shows for illustrative purposes only an example of an oxidelayer residue cleaning of one embodiment.

FIG. 7A shows for illustrative purposes only an example of an etching inthe magnetic layer of one embodiment.

FIG. 7B shows for illustrative purposes only an example of an amorphouscarbon layer residue cleaning of one embodiment.

FIG. 7C shows for illustrative purposes only an example of a highfidelity image transfer to the magnetic layer of a stack of oneembodiment.

DETAILED DESCRIPTION OF THE INVENTION

In a following description, reference is made to the accompanyingdrawings, which form a part hereof, and in which is shown by way ofillustration a specific example in which the invention may be practiced.It is to be understood that other embodiments may be utilized andstructural changes may be made without departing from the scope of thepresent invention.

General Overview:

It should be noted that the descriptions that follow, for example, interms of a method of patterning a stack is described for illustrativepurposes and the underlying system can apply to any number and multipletypes of layered imprint structures. In one embodiment the method ofpatterning a stack can be configured using a chemical application tode-scum the pattern imprinted resist layer. The method of patterning astack can be configured to include multiple oxide compounds to depositthe oxide layer and can be configured to include multiple chemicalelements or compounds to use in the chemical etching in the variouslayers to achieve high fidelity image transfer patterning of the stackusing the present invention.

In the following descriptions chemical symbols are used where O₂ meansoxygen gas; CHF₃ means trifluoromethane; Ar means argon gas, SiO₂ meanssilicon dioxide, Ta₂O₅ means tantalum pentoxide, CF₄ meanstetrafluoromethane and C₄F₅ means octafluorocyclobutane. The followingdescriptions include processes and features including RIBE meaningreactive ion beam etching; IBE meaning ion beam etching, RIE meaningreactive ion etching, UV light meaning ultraviolet light, CD meaningControl Dimensions and PFP meaning Pattern Fabrication Process. Thechemical symbols, process abbreviations and layer descriptions may beused interchangeably with their full text descriptions maintaining thesame meaning.

FIG. 1 shows a block diagram of an overview of a method of patterning astack of one embodiment. FIG. 1 shows an overview of a method of imagetransfer using an oxide layer wherein replacing a metal layer in apattern fabrication process with an oxide layer 100 preventscontaminating of the amorphous carbon layer during milling or etching.Chemical etching of the non-metallic oxide layer will prevent anymetallic residue, which may result in increased bias and fidelityaffection. The imprint layered structure with an oxide layer allows useof chemical etch 110 processes to pattern a stack of one embodiment.

The imprint layered structure with an oxide layer may includewell-defined nanostructures of various thicknesses. The nanostructuresprovide well-defined topology, composition and functionality. Ion beamscreate chemical reactions using chemical gases injected into the beamswhich act as reactive agents for chemical etching of the imprintstructure layers. The precisely positioned ion beam coupled with achemical reactive agent may be used to remove surface structures withnanometer precision and in virtually any desired three-dimensionalshapes of one embodiment.

The imprint structure layers include an imprint resist layer. A step toimprint resist layer with a pattern template 115 is processed afterdeposition of the resist layer. A template with for example abit-patterned topography is placed on the resist layer. The template maybe a mirrored topography that includes recesses. The recesses are filledin by the resist material through capillary action. The imprint resistlayer may be configured to cure or harden when exposed to UV light. Thetemplate is removed after the UV light curing. The surface of thehardened resist layer has the pattern topography transferred by usingthe template of one embodiment.

After the imprint of the resist layer is completed and the templateremoved a residual layer (scum) is left on a top of the oxide layer. Ascum on the surface of the imprint resist layer may harden more rapidlyand cause ion beam deflections which may result in poorly definedunderlying etched surfaces and structures. The method of patterning astack allows a chemical de-scum of pattern imprinted resist layer 120 tobe performed of one embodiment.

The chemical de-scum process is used to remove the residual layer (scum)left on top of the oxide layer. The post imprint scum has varyingthicknesses from feature to feature (dot to dot) within the samemagnetic stack or disk. The variations in scum thicknesses persistbetween the variations of one magnetic stack to another.

A result of scum thickness variations is the continual adjustments ofthe processing time during an oxide etching. A stack is processed usingexposure in plasma during an oxide etch for a period of time. The depthof the milling or etch of the oxide layer is controlled by the durationof the exposure time. Inconsistent mill depths of the oxide layer due toscum thickness variations may result in the possibility of CD variationand incomplete milling of the oxide layer. The chemical de-scum ofpattern imprinted resist layer 120 resolves the continual adjustments ofthe plasma exposure times caused by the scum thickness variations andincreased possibility of CD variation and incomplete milling of theoxide layer. The chemical de-scum process using oxygen gas as a reactiveagent may include a reactive ion beam etching process (RIBE) or ReactiveIon Etching (RIE). The removal of the resist layer scum using a chemicalprocess is fast and cost effective of one embodiment.

The method of patterning a stack allows use of chemical etch 110processes to pattern the remaining imprint layers. Chemical etching mayinclude processes such as reactive ion beam etching. In one embodiment astep may include oxide layer RIBE with CHF₃ 130. In this step reactiveion beam etching may be used to etch or remove a portion of the oxidelayer to create the pattern structure in the oxide layer. A chemicalsuch as trifluoromethane (CHF₃) is used as a reactive agent. The ionbeam is guided into the patterned areas to be removed and the CHF₃ gasis introduced to cause the portions of the oxide layer to be removed toreact and vaporize. The reaction is controlled to remove only the oxidelayer by the selection of the chemical reactive agent. The oxide layeris configured to include materials that are non-metallic and includematerials wherein metals in the materials can be chemically etched toprevent metals from contaminating the amorphous carbon layer below. Thechemical etching of the oxide layer is fast, cost effective and resultsin decreased control dimensions bias and fidelity affection of oneembodiment.

The patterning process progresses from one layer to the underlying layerin steps. The previously patterned layer becomes the mask for theunderlying layer. Residue of the materials from prior patterned layercreating a mask may be deposited on the underlying layer yet to bepatterned. The chemical etching of the oxide layer may deposit residueon the underlying amorphous carbon layer of one embodiment.

A step is included in the method of high fidelity image transferring topattern a stack that may include a post oxide etch residue cleaning withCHF₃ 135. The chemical etch for cleaning oxide layer residue from theamorphous carbon layer prior to the patterning process of the amorphouscarbon layer. The post oxide etch residue cleaning with CHF₃ 135 is ashort exposure time period that removes residue but leaves the oxidemask for use in patterning the amorphous carbon layer. The postpatterning oxide layer residue cleaning process prevents residue fromdamaging the magnetic layer of one embodiment.

In one embodiment the next step may include using a chemical etchingprocess to pattern the amorphous carbon layer. The chemical etchingprocess may include an amorphous carbon layer RIBE with O₂ 140. Theamorphous carbon layer is an amorphous carbon that reacts with oxygengas. A reactive ion beam etching (RIBE) process wherein oxygen gas isintroduced may be used to remove the portions of the amorphous carbonlayer in the pattern configuration. The amorphous carbon layer is anadhesive layer that after a chemical etching process is used as a maskto pattern the magnetic layer of one embodiment.

An oxide layer residue cleaning with CHF₃ 145 is performed to remove anyoxide layer etch residue and the oxide layer itself to avoid thecontaminating of amorphous carbon with this residue during IBE ofmagnetic layer. The amorphous carbon has little or no reaction with thechemistry used in the oxide layer residue cleaning with CHF₃ 145. Theresult is a clean amorphous carbon layer and underlying magnetic layersurface free of residue materials used as a mask for amorphous carbonlayer patterning such as oxide. Residue materials that remain may affectthe magnetic layer patterning quality in following process steps. Theplasma exposure used in the cleaning process would only affect surfacesin the layers that later would be milled away during magnetic layerpatterning of one embodiment.

The next step includes a chemical or non-chemical (IBE) etch of themagnetic layer to embed the pattern to be transferred by the amorphouscarbon layer mask. An ion mill process in one embodiment may be used topattern the magnetic layer IBE with Ar 150. The ion milling with argongas introduced creates a clean well-defined etch of the magnetic layer.The etching of the magnetic layer is followed by an amorphous carbonresidue cleaning with O₂ 155. The amorphous carbon residue cleaning withO₂ 155 is a chemical removal of any residue on the magnetic layer thatmay remain after the patterning of magnetic layer. The amorphous carbonresidue cleaning with O₂ 155 is the final step that leaves the magneticlayer free of any contamination from the Pattern Fabrication Process ofone embodiment.

The magnetic layer is free of any contamination that may causedegradation or deterioration of the size and position of image features.The prevention of contamination prevents affecting Control Dimensions(CD) bias and the magnetic properties of the patterned stack. The stackpatterning accomplished 160 using the method of patterning a stackprovides a simple, cost effective and fast patterning of the stack withhigh fidelity of the image transferred and high quality throughput ofone embodiment.

DETAILED DESCRIPTION

FIG. 2A shows a block diagram of an overview flow chart of a method ofpatterning a stack of one embodiment. FIG. 2 shows the method of imagetransfer using an oxide layer replacing a metal layer in a patternfabrication process with an oxide layer 100. The replacement of a metalis used to create an oxide layer imprint structure 200. The creation ofthe oxide layer imprint structure begins with a stack with magneticlayer substrate deposited 202 of one embodiment.

The next step is to deposit an amorphous carbon layer upon magneticlayer 204. The amorphous carbon layer uses an amorphous carbon to createa hard mask that will be used to transfer the pattern image to themagnetic layer. The deposition of the amorphous carbon to form theamorphous carbon layer in one embodiment may be deposited in a thicknessof 4-20 nm or more.

A step to deposit an oxide layer upon amorphous carbon layer 210 is thereplacement of the metal layer. The thickness of the oxide layer may forexample be deposited in a layer of 3 nm or more. The initial step toimage transferring is to deposit a resist layer upon oxide layer 220.The resist layer may be created using a spin-coating process of oneembodiment.

The next step to transfer the image is to imprint resist layer with apattern template 115. The pattern template may include a patterntemplate fabricated for patterned stacks such as bit-patterned ordiscrete track media. The pattern template is placed on the resist layerwith the pattern topography making contact with the resist material. Therecesses of the pattern topography are filled with resist materialsthrough capillary action. A UV light resist curing 222 hardens theresist layer including the filled recesses of one embodiment.

A step follows to remove the patterning template 224 by lifting thetemplate off when the resist layer is cured. An imprinted resistmaterial may develop an imprint resist scum 230 on the surface of theimprinted resist layer. A scum on the surface may interfere with theadditional etching processes such as deflecting beam projections. Theinterference may cause incomplete etching and reduce the fidelity of thepattern image transfer. The method of patterning a stack allows use ofchemical etch 110 processes. A step in one embodiment uses the chemicalde-scum of pattern imprinted resist layer 120 of one embodiment.

In one embodiment a chemical etch process such as O₂ reactive ion beametching 232 may be used to remove the imprint resist scum 230. Theoxygen gas injected into the ion beam reacts with the imprint resistscum 230 to dissolve or vaporize the surface scum. The chemical de-scumprocess may include processes using oxygen gas as a reactive agent suchas a reactive ion beam etching process (RIBE) and Reactive ion etch(RIE). The chemical de-scum of pattern imprinted resist layer 120 leavesthe surface of the oxide layer free of resist scum 230 residuecontamination in preparation for an image transfer to the oxide layer asshown in FIG. 2B of one embodiment.

Oxide Layer Image Transfer:

FIG. 2B shows a block diagram of a continuation of an overview flowchart of a method of patterning a stack of one embodiment. FIG. 2B showsa pattern imprinted resist layer 240 from FIG. 2A being used to transferthe image to an oxide layer 245. In one embodiment the oxide layer RIBEwith CHF₃ 130 chemical etching process may be used to etch the oxidelayer 245. The trifluoromethane is injected into the ion beam to providea reactive ion beam etching of the oxide layer 245. The patterning ofthe oxide layer using trifluoromethane as a reactive agent may includechemical etch processes such as a reactive ion beam etching process(RIBE) and reactive ion etch (RIE) of one embodiment.

The chemical etch of the oxide layer 245 prevents contamination of themagnetic layer (isolated by amorphous carbon). Etching of amorphouscarbon and Imprinted UV resist mask with chemistry chosen (CHF3) isinsignificant (chemical reaction with amorphous carbon with CHF3chemistry is very slow, compare to etching of SiO2 layer, in oneembodiment. In other embodiments the chemical etch of the oxide layer245 may include the use of other chemistry for example CF4 or C4F8, withthe same effect of one embodiment.

Oxide mask material, oxide beneath the imprinted resist, 245 may remainon the amorphous carbon layer 255. A post oxide etch residue cleaningwith CHF₃ 135 step is included to remove this residue from the amorphouscarbon layer 255 after chemical etch of the amorphous carbon layer 255.This step will prevent oxide materials from contaminating the magneticlayer 265. A short exposure time period during the post oxide etchresidue cleaning with CHF₃ 135 step will remove the oxide residuedeposits on the amorphous carbon layer 255 and leave the patterned oxidelayer 250 intact. The oxide mask is used in patterning the amorphouscarbon layer 255 of one embodiment.

A next step in one embodiment includes the amorphous carbon layer RIBEwith O₂ 140 which may be performed in the amorphous carbon layer 255.The patterning of the amorphous carbon adhesive layer may include achemical etch using oxygen gas as a reactive agent including a reactiveion beam etching process, or RIBE. The O₂ chemistry will remove thepattern imprinted resist layer 240 materials for example at anaccelerated etch rate such as 5 times faster than the etch rate of theamorphous carbon during the patterning of the amorphous carbon layer255. The accelerated etch of the resist materials removes the patternedimprinted resist layer 248 materials completely during etch of theamorphous carbon layer 255. The portions of the amorphous carbon layer255 to be removed in the pattern design are dissolved or vaporized bythe oxygen gas that is injected into the ion beam. The reactive ion beametching of the amorphous carbon layer 255 results in high fidelityincluding size and position control in the pattern image transfer of oneembodiment.

Etch of the patterned oxide layer 250 and patterned amorphous carbonlayer 260 may leave oxide residue on the on patterned amorphous carbonlayer (255). The oxide residue may poison the amorphous carbon layer 260after the magnetic layer 265 patterning. An oxide layer residue cleaningwith CHF₃ 145 is used to remove any oxide residue and also removes thepatterned oxide layer 258. The oxide layer residue cleaning with CHF₃145 may include chemical etch process using CHF3 chemistry such as RIBEor RIE. The removal of the oxide materials leaves the magnetic layer 265and remaining portion of amorphous carbon layer 255 free fromcontamination prior to the patterned layer magnetic layer 265 patterningprocesses of one embodiment.

Magnetic Layer Patterning:

FIG. 2C shows a block diagram of a continuation of an overview flowchart of a method of patterning a stack of one embodiment. FIG. 2C showsin one embodiment an etch process step in the magnetic layer 265. Thisstep may include an IBE with Ar in magnetic layer 280 to transfer thepattern image using the patterned amorphous carbon layer 260 mask. TheIBE in magnetic layer 280 may include using a non-chemical etch forexample an ion mill or milling process such as an ion beam etchingprocess using argon gas. The argon gas is injected into the ion beam.The injected Ar and ion beam act to dissolve or vaporize those portionsof the magnetic layer 265 to be removed in the patterning imagetransfer. The IBE with Ar in magnetic layer 280 results in high fidelityof the image transfer of one embodiment.

A final step in the method of patterning a stack may include theamorphous carbon residue cleaning with O₂ 155. The amorphous carbonresidue cleaning with O₂ 155 removes pattern imprinted amorphous carbonlayer 268 and any amorphous carbon layer 255 residue deposited duringthe magnetic layer 265 etching process. The amorphous carbon residuecleaning with O₂ 155 using O₂ chemistry is easily accomplished sincethere is no contamination associated with metallic and/or Oxide residuemixed up with the amorphous carbon. The amorphous carbon residuecleaning with O₂ 155 leaves the surfaces of the patterned magnetic layer270 free from contamination. This will leave the surface of stack ormedia clean of any residue, for the purpose of general stack or mediause for example in hard drives to minimize the head/stack or media spacelosses incurred by any remaining residue. The stack patterningaccomplished 160 provides high fidelity of the image transfer, highdefinition of the pattern and higher quality in the completed stacks ofone embodiment.

The steps of the method of patterning a stack results in stackpatterning accomplished 160 with simplicity and prevention of increasedbias and pattern dislocation. The method of high fidelity imagetransferring to pattern a magnetic stack using an oxide layer allowschemical etch processes to transfer the pattern image with high fidelityin stack structures such as bit-patterned and discrete track media in apattern fabrication process of one embodiment.

Oxide Layer Imprint Structure:

FIG. 3A shows for illustrative purposes only an example of an oxidelayer imprint structure of one embodiment. FIG. 3A shows an oxide layerimprint structure 300 using the method of high fidelity imagetransferring to pattern a magnetic stack using an oxide layer forreplacing a metal layer in a pattern fabrication process with an oxidelayer 100. The oxide layer 245 has replaced a metal layer in a PFP. Theoxide layer 245 may include a deposition thickness of the oxide layersuch as 1-3 nm or more for example using compounds such as silicondioxide (SiO₂) or Tantalum Pentoxide (Ta₂O₅). The compounds used to formthe oxide layer 245 contain no metal. The non-metallic oxide layer isused to prevent contamination of the amorphous carbon layer 255 withun-deposited metallic residue. The oxide layer imprint structure 300includes the imprint resist layer 310, the oxide layer 245, theamorphous carbon layer 255 and the magnetic layer 265 of one embodiment.

Patterning Template:

FIG. 3B shows for illustrative purposes only an example of templatepatterning in the resist layer of one embodiment. FIG. 3B shows theplacement or setting of the patterning template 320 on the resist layer310 of a stack being fabricated. The patterning template 320 illustratesthe reverse image of the pattern design. Recesses from the bottomsurface of the patterning template 320 will be used to form domaintrenches after the patterning is completed. The projections toward thebottom of the patterning template 320 will form islands or tracks in apatterned stack such as a bit-patterned or discrete track stack. Thechemical etch processes allowed by the method of patterning a stack willbe used to etch the pattern in the oxide layer 245, amorphous carbonlayer 255 and magnetic layer 265 of one embodiment.

Resist Layer UV Light Curing:

FIG. 4A shows for illustrative purposes only an example of UV lightresist curing of the resist layer of one embodiment. FIG. 4A shows thepatterning template 320 after being set into place on the imprint layersstructure 200 of FIG. 2. The imprint resist layer 310 materials haveflowed through capillary action into the recesses of the patterningtemplate 320 to fill the voids. In one embodiment the imprint resistlayer 310 materials may be a spin-coated resist in a layer thickness offor example 30 nm or more. The imprint resist layer 310 layer thicknesswill be changed through the placement of the patterning template 320.The areas of the imprint resist layer 310 will be thin where thetemplate projections are closest to the oxide layer 245, amorphouscarbon layer 255 and magnetic layer 265. The filled recesses will bethicker. A process such as UV light resist curing 222 may be used toharden the imprint resist layer 310 materials. The cured imprint resistlayer 310 materials will retain the reverse topography of the patterningtemplate 320 of one embodiment.

Removing a Patterning Template:

FIG. 4B shows for illustrative purposes only an example of removing thepattern template from the resist layer of one embodiment. FIG. 4B showsthe removal of the patterning template 320 from the cured resistmaterials. The oxide layer 245 also provides high adhesion of the resistlayer. The high adhesion generates a clean resist peel or removal of thetemplate after UV irradiation of the resist layer. The patterningtemplate 320 is lifted off to reveal the pattern imprinted resist layer240. The pattern imprinted resist layer 240 may develop a resist scum400 on the surface after the patterning template 320 is removed. Theoxide layer 245, amorphous carbon layer 255 and magnetic layer 265 willbe patterned through other processes of one embodiment.

Chemical De-Scum:

FIG. 5A shows for illustrative purposes only an example of a chemicalde-scum of the pattern imprinted resist layer of one embodiment.Chemical processes may be used in the method of patterning a stack foretching and other removals of layered materials. One such chemicalprocess in one embodiment is the chemical de-scum of pattern imprintedresist layer 120. A chemical de-scum of pattern imprinted resist layer120 may include a process such as a reactive ion beam etching processusing oxygen gas as a reactive agent.

The scum that may develop on the surface of the pattern imprinted resistlayer 240 materials may cause irregularities in the projection of ionbeams used in etching the various layers. These irregularities mayinclude deflection of the ion beam path. The deflections may for exampleprevent materials from being removed within the pattern design or causethe removal of materials outside the pattern boundaries. These layermaterials removal irregularities may interfere with the properfunctioning of the patterned layers.

In one embodiment a process such as O₂ reactive ion beam etching 232 isused for removal of the resist scum 400. Injected oxygen gas in concertwith the ion beam will dissolve or vaporize the scum on the surface ofthe pattern imprinted resist layer 240. A small portion of the patternimprinted resist layer 240 may be removed to assure full removal of theresist scum 400. The O₂ reactive ion beam etching 232 prevents affectingthe oxide layer 245, amorphous carbon layer 255 or magnetic layer 265 ofone embodiment, it only does a chemical etch of thin resist scum 400layer of pattern imprinted resist layer 240.

Chemical Etching of the Oxide Layer:

FIG. 5B shows for illustrative purposes only an example of an etching inthe oxide layer of one embodiment. The chemical etch of the oxide layer245 prevents contamination of the amorphous carbon layer 255 withun-deposited metal that would create increased bias. The patternimprinted resist layer 240 is used as a mask to pattern the oxide layer245. A chemical etch such as a reactive ion beam etching process usingchemistry such as trifluoromethane (CHF₃), tetrafluoromethane (CF₄) oroctafluorocyclobutane (C₄F₈) as a reactive agent may for example etchthe oxide layer fast, while etching of the amorphous carbon layer 255 issuppressed of one embodiment.

The oxide layer 245 in one embodiment may be etched using the oxidelayer RIBE with CHF₃ 130 which allows use of chemical etch 110 of FIG. 1processes. The trifluoromethane is introduced near the ion beamprojections to react with the oxide layer 245. The chemical reactiondissolves or vaporizes those portions of the thin oxide layer 245 in thepattern designed areas. The oxide layer RIBE with CHF₃ 130 preventsremoval of the amorphous carbon layer 255 or magnetic layer 265. Thechemical etching process creates a pattern image transfer with highfidelity. No metal is included in the oxide layer 245. The oxide layerRIBE with CHF₃ 130 prevents leaving any un-deposited metal to affectbias of one embodiment. The patterned oxide layer 245 forms a mask forpatterning the amorphous carbon layer 255 in the next step, using achemical etch.

Chemical Etching of the Amorphous Carbon Layer:

FIG. 6A shows for illustrative purposes only an example of an etching inthe amorphous carbon layer of one embodiment. FIG. 6A shows a patternimprinted resist layer 240 of FIG. 2B and a patterned oxide layer 250after the chemical etching process. In one embodiment the next step isto pattern the amorphous carbon layer 255. The method of patterning astack allows a chemical etch such as the amorphous carbon layer RIBEwith O₂ 140. The patterning of the amorphous carbon layer 255 mayinclude a chemical etch using oxygen gas as a reactive agent such as areactive ion beam etching process. The reactive agent, oxygen gas, isinjected into the area to be etched. The precisely focused ion beamcauses chemical reaction between the O₂ and the amorphous carbon layer255 materials and removes the patterned imprinted resist layer 248. Theamorphous carbon layer 255 materials to be removed in accordance withthe pattern design are dissolved or vaporized in the chemical reaction.The oxygen reactive ion beam etching of the amorphous carbon layer 255materials prevents affecting the magnetic layer 265. The resulting etchof the amorphous carbon layer 255 is clean, fast, cost effective and isproviding high fidelity of the pattern image transfer of in oneembodiment. Removal of resist mask residue 248 at this point will leaveOxide mask residue with no protection. It will allow of cleaning oxideresidue in the next step.

Oxide Layer Residue Cleaning:

FIG. 6B shows for illustrative purposes only an example of an oxidelayer residue cleaning of one embodiment. FIG. 6B shows the patternedamorphous carbon layer 260. An oxide layer residue cleaning with CHF₃145 may be used to remove any oxide layer residue and removes thepatterned oxide layer 258. The oxide layer residue cleaning with CHF₃145 may include a chemical etch process using CHF₃ chemistry with RIE orRIBE which is etching the oxide materials fast, while almost no etchingof the amorphous carbon layer materials occurs. The oxide layer residuecleaning with CHF₃ 145 leaves the patterned amorphous carbon layer 260and the magnetic layer 265 free from any contamination from oxideresidue from the patterned oxide layer 250 of FIG. 2B.

Etching of the Magnetic Layer:

FIG. 7A shows for illustrative purposes only an example of an etching inthe magnetic layer of one embodiment. FIG. 7A shows the patternedamorphous carbon layer 260 being used as the pattern mask for the IBEwith Ar in magnetic layer 280. This mill process of patterning themagnetic layer 265 may include sputter-etch such as an ion beam etchingprocess using argon gas as an agent to pattern the magnetic layer. Argonis one of the noble gases, is stable and resists bonding with otherelements. The argon gas is injected into the ion beam and the magneticlayer 265 materials to be removed according to the pattern design aredissolved or vaporized in the process. The exposure time and intensityof the precisely guided focused ion beam can be controlled to accuratelyset the depth of the etching in one embodiment.

Amorphous Carbon Layer Residue Cleaning:

FIG. 7B shows for illustrative purposes only an example of an amorphouscarbon layer residue cleaning of one embodiment. FIG. 7B shows theamorphous carbon residue cleaning with O₂ 155 and may include the use ofother gases, or their mixture using processes such as RIE or RIBE withoxygen gas as a reactive agent. The O₂ chemistry easily etches thepatterned amorphous carbon layer 260 of FIG. 2C and any residue from thepatterned amorphous carbon layer 260 of FIG. 2C milling processes. TheO₂ chemistry has insignificant affect on the patterned magnetic layer270. The amorphous carbon residue cleaning with O₂ 155 removes thepatterned amorphous carbon layer 268 and any amorphous carbon layer 255of FIG. 2B patterning residue resulting in the patterned magnetic layer270 being free from contamination.

High Fidelity Image Transfer Patterned Stack:

FIG. 7C shows for illustrative purposes only an example of a highfidelity image transfer to the magnetic layer of a stack of oneembodiment. FIG. 7C shows the patterned magnetic layer 270 of a stack.The patterned magnetic layer 270 is free of contamination from residueproduced in the milling of the other layers. The stack patterningaccomplished 160 using the oxide layer imprint structure 300 of FIG. 3Aproduces the high fidelity image transfer in a PFP used for example forbit-patterned and discrete track media of one embodiment.

The foregoing has described the principles, embodiments and modes ofoperation of the present invention. However, the invention should not beconstrued as being limited to the particular embodiments discussed. Theabove described embodiments should be regarded as illustrative ratherthan restrictive, and it should be appreciated that variations may bemade in those embodiments by workers skilled in the art withoutdeparting from the scope of the present invention as defined by thefollowing claims.

1. A method of fabricating a stack, comprising: replacing a metal layerof a stack imprint structure with an oxide layer; patterning the oxidelayer using chemical etch processes to transfer the pattern image; andcleaning etch residue from the stack imprint structure to substantiallyprevent contamination of the metal layers.
 2. The method of claim 1,further comprising cleaning oxide layer etch residue remaining on anamorphous carbon layer, chemically etching the amorphous carbon layer,cleaning amorphous carbon layer etch residue remaining on the magneticlayer and patterning the magnetic layer, wherein the cleaning oxidelayer and the cleaning amorphous carbon layer prevents contamination ofthe magnetic layer.
 3. The method of claim 2, further comprisingdepositing one or more materials to form the oxide layer, wherein theoxide layer is configured to be chemically etched.
 4. The method ofclaim 1, further comprising using a chemical de-scum to remove surfacescum that develops on the surface of an imprint structure resist layerafter being imprinted.
 5. The method of claim 4, wherein using thechemical de-scum process includes using oxygen gas as a reactive agentwith a reactive ion beam etching process.
 6. The method of claim 1,wherein the patterning of the oxide layer includes chemical etchingusing trifluoromethane as a reactive agent with reactive ion beametching and reactive ion etching.
 7. The method of claim 6, wherein thechemical etch of the oxide layer Includes using a chemical etchchemistry configured to process etching the oxide layer, while etchingof an amorphous carbon layer is suppressed.
 8. The method of claim 1,wherein the patterning of the amorphous carbon layer includes using achemical etch process with oxygen gas and reactive ion beam etching. 9.The method of claim 1, wherein the patterning of the magnetic layerincludes using an argon gas etch process including ion beam etching. 10.The method of claim 1, wherein the chemical etching transfers thepattern image with a predetermined fidelity including bit-patterned anddiscrete track media pattern images.
 11. An apparatus, comprising: meansfor replacing a metal layer of an imprint structure with an oxide layerto substantially prevent metallic residue contamination of an amorphouscarbon layer; and means for patterning an imprint structure usingchemical etch processes to transfer pattern images with a predeterminedfidelity.
 12. The apparatus of 11, further comprising means fordepositing an oxide layer in an imprint structure in depositionthicknesses of the oxide layer including at least 3 nm.
 13. Theapparatus in 11 further comprising means for depositing one or morematerials to form the oxide layer, wherein the oxide layer is configuredto be chemically etched wherein amorphous carbon and imprinted resistlayers.
 14. The apparatus of 11, further comprising means for a chemicalde-scum of the imprinted resist layer using a process including areactive ion beam etching process using oxygen gas as a reactive agent.15. The apparatus of 11, further comprising means for patterning theoxide layer using a chemical etch process including reactive ion beametching using trifluoromethane as a reactive agent.
 16. The apparatus of11, further comprising means for patterning of an amorphous carbon layerusing chemical etching including reactive ion beam etching includingoxygen gas as a reactive agent.
 17. The apparatus of 11, furthercomprising means for patterning the magnetic layer using an etch processincluding an ion beam etching process using argon gas as an agent.
 18. Astack imprint structure, comprising: an imprint structure; an oxidelayer, wherein the oxide layer includes one or more materials configuredto be etched using chemical etching to pattern the imprint structure andwherein pattern images are transferred to the imprint structure with apredetermined fidelity.
 19. A stack imprint structure of 18, wherein theoxide layer materials are configured to be chemically etched usingchemistry for patterning, while amorphous carbon layers and imprintedresist layers resist being etched by the same chemistry.
 20. The stackimprint structure of claim 18, wherein the oxide layer depositedmaterials is configured to include a thickness of at least 3 nm.
 21. Thestack imprint structure of claim 18, wherein the oxide layer isconfigured to be chemically etched using reactive ion beam etching withtrifluoromethane as a reactive agent to avoid etching other imprintstructure layers during the oxide layer etch and to prevent fidelitydegradation of other layers due to mask erosion and un-controlled etch.22. The stack imprint structure of claim 18, wherein oxide layer etchresidue is configured to be removed using etching processes whereintrifluoromethane is introduced to remove oxide etch residue after anamorphous carbon layer patterning process.
 23. The stack imprintstructure of claim 18, wherein an imprint structure amorphous carbonlayer is configured to include patterning of the amorphous carbon layerusing at least one of a chemical etch including reactive ion beametching or a reactive ion etching process using oxygen gas as a reactiveagent.
 24. The stack imprint structure of claim 18, wherein an imprintstructure magnetic layer is configured to include patterning of themagnetic layer using an ion beam etching process using argon gas forsputter-etch.
 25. The stack imprint structure of claim 18, wherein theimprint structure amorphous carbon layer etch residue is configured tobe removed using etching processes, wherein at least one of oxygen gasor a mixture of compatible gases are introduced to remove amorphouscarbon residue left after magnetic layer patterning.